WO2001057562A1

WO2001057562A1 - Optical component and optical apparatus comprising it

Info

Publication number: WO2001057562A1
Application number: PCT/JP2001/000624
Authority: WO
Inventors: Kazuro Kikuchi; Yuichi Takushima; Mark Kenneth Jablonski; Yuichi Tanaka; Haruki Kataoka; Noboru Higashi; Kenji Furuki
Original assignee: Oyokoden Lab Co., Ltd.
Priority date: 2000-02-02
Filing date: 2001-01-31
Publication date: 2001-08-09
Also published as: AU2001230530A1

Abstract

In an optical communication system using an optical fiber, it is forecasted that correct communication can not be ensured by a conventional wavelength dispersion compensation method due to increase in communication bit rate and communication distance and tertiary or higher-order wavelength dispersion compensation is required. But any effective countermeasure has been not proposed for tertiary wavelength dispersion compensation. A multilayer film (300) comprising at least four reflection layers (305, 304, 303, 302) having reflectance increasing sequentially from the incident side of signal light is employed as a tertiary wavelength dispersion compensation element in order to compensate for tertiary wavelength dispersion by generating a group velocity delay in the signal light. The thickness of the multilayer film as the optical path length is set equal to an integral multiple of a quarter of wavelength.

Description

Description Optical components and optical devices using the same

The present invention relates to an element capable of compensating for tertiary chromatic dispersion (hereinafter, also simply referred to as dispersion) generated in optical communication using an optical fiber for a transmission line (hereinafter, an element capable of changing tertiary dispersion, or The present invention relates to an optical component having a chromatic dispersion compensating element, which is also simply referred to as a dispersion compensating element, and an optical device using the same. The third-order dispersion compensator itself is also included in the optical component having the third-order dispersion compensator.

In optical communication using optical fibers for communication transmission lines, there is a demand for longer-distance communication transmission lines and higher-speed communication bitrates, along with advances in use technology and expansion of the range of use. In such an environment, chromatic dispersion generated when transmitting an optical fiber becomes a serious problem, and various attempts have been made to compensate for chromatic dispersion. At present, the second-order chromatic dispersion is a major problem, and various compensations have been proposed, some of which have been effective.

However, as the demand for optical communication becomes higher, compensation for the second-order chromatic dispersion during transmission alone becomes insufficient, and compensation for the _third- order chromatic dispersion is becoming an issue. Hereinafter, a conventional method of compensating for the second-order chromatic dispersion will be described with reference to FIGS.

Fig. 8 is a diagram illustrating the dispersion versus wavelength characteristics of a single-mode optical fiber (hereinafter, also referred to as SMF), a dispersion compensating fiber, and a dispersion shift fiber (hereinafter, also referred to as DSF). In FIG. 8, reference numeral 8001 is a graph showing the dispersion-wavelength characteristic of the SMF, 8002 is a graph showing the dispersion-wavelength characteristic of the dispersion compensating fiber, and 803 is a graph showing the dispersion-wavelength characteristic of 0 SF. And the vertical axis is dispersion and the horizontal axis is wavelength. As is evident from Fig. 8, in the SMF, the dispersion increases as the wavelength of the light input to the fiber increases from 1.3 µm to 1.8 µm. Dispersion decreases with increasing length from 1.3 111 to 1.8 μm. In the DSF, the dispersion decreases as the wavelength of the input light increases from 1.2 / ^ 1 to around 1.55 μπι, and the wavelength shifts from around 1.55 μπι to 1.8 μηι. As the length increases, the variance increases. The DSF has the characteristic that the dispersion is almost constant with changes in wavelength when the wavelength of the input light is around 1.55 μm. Fig. 7 is a diagram explaining the method of compensating for the second-order chromatic dispersion. (A) shows the wavelength-time characteristic, and (B) shows the second-order chromatic dispersion compensation using SMF and dispersion compensating fiber. (C) is a diagram for explaining an example of a transmission line using only SMF. In FIG. 7, reference numerals 70 1 and 71 1 denote graphs showing the characteristics of signal light before being input to the transmission line, 730 denotes a transmission line constituted by SMF 731, 70 2 and 71 2 is a graph showing the characteristics of the signal light output from the transmission path 7 330, 7 2 0 is a transmission path composed of the dispersion compensating fiber 7 2 1 and SMF 7 2 2, 7 0 3 and 7 13 are transmission 26 is a graph showing the characteristics of the signal light output from the path 720. Reference numerals 704 and 714 are graphs showing characteristics of the signal light when the signal light is subjected to a desirable third-order dispersion compensation described later according to the present invention described later. Almost matches 1 1. Graphs 71, 702, 703, and 704 are graphs with the vertical axis representing wavelength and the horizontal axis representing time (or time), respectively. Graphs 711, 712, 71 3, 7 and 14 are graphs with the vertical axis representing light intensity and the horizontal axis representing time (or time). Reference numerals 724 and 732 are transmitters, and reference numerals 725 and 735 are receivers.

As described above, the conventional SMF increases the dispersion as the wavelength of the signal light increases from 1.3 m to 1.8 m. This causes a speed delay. In the transmission line 730 composed of SMF, for example, the signal light with a wavelength of around 1.55 μm has a longer delay on the long wavelength side than on the short wavelength side during transmission. As shown in 7 1 2 For example, in high-speed long-distance transmission, the signal light that has changed in this way may not be able to be received as an accurate signal because it overlaps the preceding and following signal lights. Conventionally, in order to solve this problem, dispersion is compensated using a dispersion compensating fiber as shown in Fig. 7 (B). U) The conventional dispersion compensating fiber solves the problem of SMF in which the dispersion increases as the wavelength increases from 1.3 μπι to 1.8 / im. The dispersion is designed to decrease as ηι increases to 1.8 μm. The dispersion compensating fiber can be used by connecting the dispersion compensating fiber 721 to the SMF 722, for example, as shown by a transmission line 720 in FIG. In the above transmission line 720, for example, the signal light having a wavelength of about 1.55 / zm is greatly delayed on the long wavelength side as compared with the short wavelength side in the SMF 722, and is transmitted in the dispersion compensation fiber 721, for example. Since the short wavelength side is delayed more than the long wavelength side, the degree of the change can be suppressed more than the changes shown in the graphs 702 and 712 as shown in the graphs 703 and 713.

However, in the above-described conventional method of compensating for the second-order chromatic dispersion using the dispersion compensating fiber, the chromatic dispersion of the signal light transmitted through the transmission line is represented by the state of the signal light before being input to the transmission line. Dispersion compensation cannot be performed up to the shape of 1 and the limit is to compensate up to the shape of graph 703. As shown in the graph 703, the center of the wavelength of the signal light is not delayed as compared with the short wavelength side and the long wavelength side, and only the short wavelength side and the long wavelength side of the signal light are delayed. Then, a ripple may occur as shown in the graph 713.

These phenomena are becoming serious problems such as the inability to receive accurate signals as the need for longer transmission distances and higher communication speeds increases in optical communications. For example, in high-speed communication with a communication bit rate of 20 Gbps (20 gigabits per second) or more, these phenomena are of considerable concern. This is a very serious issue in communications that transmit over 0.0 km or transmit over a distance of the order of 100 km at 800 Gbps. In high-speed communication, it is considered difficult to use a conventional optical fiber communication system. For example, the necessity of changing the material of the optical fiber itself has been called out, which has become a serious economic problem in system construction. I have.

Compensation for such chromatic dispersion is difficult only by compensating for second-order chromatic dispersion, but it is necessary to compensate for third-order chromatic dispersion.

Conventionally, second-order chromatic dispersion is reduced for light with a wavelength of around 1.55 μm. Although there is a DSF as an optical fiber (hereinafter, also simply referred to as a fiber), this fiber cannot perform third-order chromatic dispersion compensation, which is the subject of the present invention.

In practical use of high-speed optical communication and long-distance communication, the third-order chromatic dispersion is gradually recognized as a major problem, and compensation of which is becoming an important issue. Many attempts have been made to solve the third-order chromatic dispersion compensation problem, but a third-order dispersion compensation element or compensation method that can completely solve the conventional problems has not yet been realized.

As an example of a third-order dispersion compensating element, which is a main element constituting an optical component and an optical device used in the above-described third-order dispersion compensating method, a dielectric multilayer film proposed by the present inventors has the following three-dimensional structure. We succeeded in compensating for chromatic dispersion, and were able to make significant progress in conventional optical communication technology (Japanese Patent Application No. 11-34-64-44). However, for further development of optical communication technology, it is desirable to further improve the characteristics of the third-order dispersion compensating element such as the dielectric multilayer film. Further improvements are expected. The present invention has been made in view of such a point, and an object of the present invention is to use a dielectric or other multilayer film element having a good group velocity delay-one wavelength characteristic which has not been obtained conventionally. To provide an optical component configured to perform third-order or higher chromatic dispersion compensation and an optical device using the same. Disclosure of the invention

In order to achieve the object of the present invention, the optical component and the optical device of the present invention are characterized by using a third-order chromatic dispersion compensating element.

More specifically, the optical component and the optical device of the present invention use the center wavelength of the incident light as the optical path length for the light having the center wavelength of the incident light (hereinafter, also simply referred to as the optical path length). A multilayer film that has at least seven laminated films whose integral film thickness (hereinafter simply referred to as “film thickness” or “film thickness”) is an integral multiple of 1/4 (λ / 4) An element having a multilayer film formed so that the multilayer film has at least four light reflection layers (hereinafter, also simply referred to as a reflection layer) with respect to incident light is referred to as a third-order wavelength dispersion compensation element. It is characterized by using

In order to enhance the effects of the present invention, in the present invention, A multilayer film composed of at least seven layers, and a multilayer film composed of the at least seven layers is sometimes collectively referred to as a multilayer film, unless otherwise required. Of these, although not limited to this, for example, seven or nine layers are configured so that reflective layers and light transmissive layers (hereinafter, also simply referred to as transmissive layers) are alternately formed. In the case of the seven layers, four reflective layers and three transmissive layers are formed, and in the case of the nine layers, five reflective layers and four transmissive layers are formed. And, when considered as an optical path length between the seven layers or the nine layers, each interval is configured such that at least adjacent intervals are not equal, and particularly preferably, all intervals are equal. It is characterized by not being configured.

The third-order dispersion compensating element of the present invention is characterized by having three or four cavities having different resonance (resonance) wavelengths.

In the present invention, the seven-layered multilayer film is formed by sequentially ordering the seven layers from a first layer, a second layer, a third layer, a fourth layer, a fifth layer, and a sixth layer from one side in the thickness direction of the multilayer film. When the reflection layers are referred to as a first layer, a third layer, a fifth layer, and a seventh layer, and their reflectivities are R1, R3, R5, and R7, respectively, R1 ≤ R 3 ≤ R 5 ≤ R 7, and the nine-layered multilayer film is a first layer, a second layer, and a third layer in order from one side in the thickness direction of the multilayer film. , The fourth layer, the fifth layer, the sixth layer, the seventh layer, the eighth layer, and the ninth layer, when the reflecting layer is the first layer, the third layer, the fifth layer, the seventh layer, and the ninth layer. Let R 1, R 3, R 5, R 7, and R 9 denote the reflectivity, respectively, so that R 1 ≤ R 3 ≤ R 5 ≤ R 7 ≤ R 9 It is a feature. When the seven-layer or nine-layer multilayer film is formed on the substrate, the substrate may be on the first layer side, and the substrate may be on the seventh or ninth layer side. good. A substrate may be provided on one side of the seven-layer or nine-layer multilayer film, and a layer different from the multilayer film, for example, an antireflection film or a protective layer may be formed on the other side.

As an example of the third-order dispersion compensating element of the present invention, the multilayer film has a film thickness of 1/4 times L and a higher refractive index (layer H) and a film thickness of 1 / λ. The multilayer film is composed of a plurality of layers each including a layer (layer L) having a lower refractive index of 4 times, and the multilayer film is formed in order from one side in the thickness direction of the multilayer film. A layer composed of three sets of layers (hereinafter also referred to as LH layers or LH films) that are combined in order, Layer L and Layer L Layer composed of 32 sets of combined layers (hereinafter also referred to as LL layer or LL film), composed of 1 layer H and 5 sets of LH layers Layers composed of 43 sets of LL layers, 1 layer H and 8 sets of LH layers, and 18 layers of LL layers And a multi-layered film formed by each layer of a layer constituted by laminating one layer H and 15 sets of LH layers.

Further, as another example of the tertiary dispersion compensating element of the present invention, the multilayer film is formed by laminating two sets of LH layers in order from one side in the thickness direction of the multilayer film. , Layer composed of 54 sets of LL layers, layer composed of 1 layer H and 3 sets of LH layers, and 70 sets of LL layers laminated A layer composed of one layer H and five sets of LH layers, a layer composed of 57 sets of LL layers, and one layer H Layers composed of 7 sets of layers and LH layers, layers composed of 47 sets of LL layers, 1 layer H and 15 sets of LH layers And a multilayer film formed of layers formed by laminating the above. In order to enhance the effect of the present invention, the multilayer film has a film thickness, which is considered to be the center wavelength of incident light and the optical path length for incident light, is 1 / It is characterized in that it is composed of a number of layers that are four times as many as unit layers. Each reflective layer has a thickness of 1/4 wavelength and relatively high reflectivity (layer H), and a thickness of 1/4 wavelength and relatively low reflectivity (layer H). It is characterized by being composed of a multilayer film by a combination of the above.

Since occupying become the effects of the present invention large, the third-order dispersion compensation device of the present invention is primarily, S i (silicon), G e (Germa - © beam), T i 0 ₂ (titanium dioxide ), T a ₂ 0 ₅ (tantalum pentoxide), one or both of the layer formed by the N b ₂ O _s (niobium pentoxide) of any layer and S io formed by ₂ (silicon dioxide) It is characterized by having a multilayer film composed of a combination of the following.

Since occupying become the effects of the present invention large, formation of a layer consisting of either S i, G e, T i 〇 _{_{_{2, T a 2 0 5,}}} N b 2 〇 ₅ the layer H is mainly is, the layer L is characterized by being formed by a layer consisting of S i 〇 ₂ as the main. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram illustrating a three-cavity one-dimensional chromatic dispersion compensator according to the present invention.

FIG. 2 is a diagram illustrating a 4-cavity tertiary chromatic dispersion compensator according to the present invention.

FIG. 3 is a view for explaining a three-cavity-dielectric multilayer tertiary chromatic dispersion compensating element as one embodiment of the present invention.

FIG. 4 is a diagram showing a group velocity delay time-wavelength characteristic of the third-order chromatic dispersion compensator of FIG.

FIG. 5 is a view for explaining a four-cavity-dielectric multilayer tertiary chromatic dispersion compensating element as one embodiment of the present invention.

FIG. 6 is a diagram showing a group velocity delay time-wavelength characteristic of the third-order chromatic dispersion compensator of FIG.

Figure 7 is a diagram explaining the chromatic dispersion compensation method. (A) shows the wavelength-time characteristic, (B) shows the second-order chromatic dispersion compensation using a dispersion compensation fiber, and (C) shows the single mode optical fiber. FIG. 3 is a diagram illustrating a transmission path.

FIG. 8 is a diagram illustrating dispersion-wavelength characteristic curves of various fibers. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings used in the description schematically show the dimensions, shapes, arrangement relations, and the like of the components so that these inventions can be understood. Also, in each of the drawings, the same components are denoted by the same reference numerals, and redundant description may be omitted.

FIG. 1 is a diagram illustrating an example of a multilayer film used for a third-order dispersion compensating element of the present invention using a model. In FIG. 1, reference numeral 100 denotes a multilayer film, 101, 102, and 103 denote a reflective layer having a reflectance of less than 100% (hereinafter also referred to as a reflective film), and 104 denotes a reflectance. However, about 100% is a reflective layer, 105, 106, and 107 are transmissive layers, and 111, 112, and 113 are cavities.

The reflectance R (101), R of each of the reflective layers 101, 102, 103, 104 in Fig. 1 (1 0 2), R (1 0 3), R (1 0 4) are R (1 0 1) ≤ R (1 0 2) ≤ R

(1 0 3) ≤ R (104).

Here, the reflectance of each reflective layer is formed so as to gradually increase in the thickness direction of the multilayer film 100. Then, the conditions for forming each reflective layer are selected so that the intervals when considered as the optical path length between each reflective layer are different from each other. By doing so, the design accuracy of the reflectance of each reflective layer can be relaxed, and a multilayer film used in the tertiary dispersion compensating element of the present invention is formed by combining a unit film having a thickness of a quarter wavelength. Thus, a third-order dispersion compensator with high reliability and low manufacturing cost can be provided at low cost.

FIG. 2 is a diagram illustrating an example of a multilayer film used for the third-order dispersion compensating element of the present invention using a model. In FIG. 2, reference numeral 200 denotes a multilayer film, 201, 202, 203, 204 a reflection layer having a reflectance of less than 100%, and 205 a reflectance of about 10%. 0% of the reflective layer, 206, 207, 208, and 209 are transmissive layers, and 211, 212, 213, and 214 are cavities.

The reflectance R (201), R (202), R (203), R of each reflective layer 201, 202, 203, 204, 205 in FIG. (2 0 4), R (2 0 5) is the relation of R (2 0 1) ≤ R (2 0 2) ≤ R (2 0 3) ≤ R (2 0 4) ≤ R (2 0 5) It is in. That is, the reflective layers are formed so that the reflectivity of each reflective layer sequentially increases in the thickness direction of the multilayer film 200. The conditions for forming each reflective layer are selected so that the intervals when considered as the optical path length between each reflective layer are different from each other. By doing so, the design accuracy of the reflectance of each reflective layer can be relaxed, and the combination of unit films having a thickness of a quarter wavelength makes it possible to form a multilayer film used in the tertiary dispersion compensating element of the present invention. A third-order dispersion compensating element that can be formed, has high reliability, and is inexpensive to manufacture can be provided at low cost.

Furthermore, the loss (insertion loss) on the signal light when the dispersion generated in the signal light is compensated by the dispersion compensating element using the multilayer film of the present invention is extremely small, which is a very great advantage in practical use. is there.

(Example 1)

FIG. 3 is a diagram for explaining a dielectric multilayer film used in an example of the present invention. A dielectric multilayer film as a three-cavity-first-order chromatic dispersion compensating element as one embodiment of the present invention will be described with reference to FIG.

In FIG. 3, reference numeral 300 denotes a dielectric multilayer film, reference numeral 301 denotes BK-7 (glass) as a substrate for forming the dielectric multilayer film, and reference numeral 300 denotes a first reflective layer which is an LH layer. Are formed by laminating three sets, and 304 is a second reflective layer having one layer H and below it (that is, means the substrate 301 side of the one layer H). The same applies to the following.) LH layers are formed by laminating 5 sets, and 303 is a third reflective layer consisting of 1 layer H and 8 sets of LH layers beneath it. Reference numeral 302 denotes a fourth reflection layer, which is formed by laminating one layer H and 15 sets of LH layers below the layer H. Reference numeral 308 denotes a first transmission layer formed by stacking 32 sets of LL layers, and reference numeral 307 denotes a second transmission layer formed by stacking 43 sets of LL layers. Reference numeral 306 denotes a third transmission layer, which is formed by laminating 18 sets of LL layers. Reference numeral 320 denotes an arrow indicating the direction of light incident on the dielectric multilayer film 300, and reference numeral 330 denotes an arrow indicating the direction of light emitted from the dielectric multilayer film 300.

Reference numeral 311 denotes a first cavity (resonator) between the first reflection layer 304 and the second reflection layer 304, and 312 denotes a second reflection layer 304. A second cavity between the third reflective layer 303 and a third cavity 31 between the third reflective layer 303 and the fourth reflective layer 302.

The above-mentioned LH layer is composed of a layer L formed of a film formed by ion-assist deposition of SiO _{2 having} a quarter wavelength thickness (hereinafter also referred to as an ion-assist film), and a quarter-wave thickness layer. T i ◦ are composed of a layer H formed by _two Ion'ashisu DOO film, the S i O ₂ of Ion'ashisu bets film (the layers) 1 layer and T i 0 ₂ Ion'ashisu preparative layer (layer H) One combined layer is referred to as one set of LH layers. For example, “stacking three sets of LH layers” means “layer L, layer H, layer L, layer H, layer L, layer Each layer is formed by layering one by one in the order of H. "

Similarly, layers of the LL is called the thickness was formed overlapping two layers L which is composed of Ion'ashisu preparative layer of S i 〇 ₂ quarter wavelengths layer substantially one set of LL. Therefore, for example, “stacking 32 sets of LL layers” means “formed by stacking 64 layers L”. The thickness of each of the first, second, third, and fourth reflective layers is 64 times, 11 times, 4 times, 17 times, 4 times, and 3 times, respectively. The thicknesses of the second, third and third transmission layers are 644 times, 864 times, and 364 times, respectively.

The reflectivity of the first, second, third, and fourth reflection layers increases in the order of the first, second, third, and fourth reflection layers, and is 52.4% and 95.3%, respectively. , 99.5% and 100%. It is preferable that each of the above reflectivities be within 3% of the above values. Furthermore, in order to quantitatively provide an excellent dispersion compensating element having characteristics as shown in FIG. 4 described below, the reflectance of the first reflective layer must be 50.0% or more and 68.0 or more. % Or less, the reflectance of the second reflective layer is 92.0% or more and 99.0% or less, the reflectance of the third reflective layer is 99.0% or more and 99.8% or less, It is preferable that the reflectivity of the fourth reflective layer be 99.8% or more.

FIG. 4 shows the incident light of the tertiary dispersion compensating element using the dielectric multilayer film of FIG. 3 when the incident light incident from the direction of arrow 320 exits in the direction of arrow 330. Is a graph showing the group velocity delay time-wavelength characteristic curve (curve indicated by reference numeral 401 in the figure) with respect to, where the vertical axis is the group velocity delay time and the horizontal axis is the wavelength shift from the center wavelength of the incident light. is there. The center wavelength on the horizontal axis is 1550 nm, and the maximum group velocity delay time is 7.2 ps (picoseconds). The bandwidth as a third-order dispersion compensating element is about 2 nm.

Also, the group velocity delay time of each wavelength of the reflected light obtained by the resonance can be changed by adjusting the thickness of each layer, and the incident angle of the incident light with respect to the dielectric multilayer film 300 Adjustment is also possible by changing.

(Example 2)

Next, a dielectric multilayer film as a four-cavity tertiary dispersion compensating element will be described as an embodiment of the present invention with reference to FIG.

In FIG. 5, reference numeral 500 denotes a dielectric multilayer film, 501 denotes BK-7 (glass) as a substrate on which the dielectric multilayer film is formed, and 506 denotes a first reflection layer and an LH layer. 505 is a second reflective layer and one layer H and a layer below it (that is, the one layer H means the substrate 501 side). The same applies to the following.) Three layers of LH are laminated, and 504 is a third reflective layer composed of one layer H and five sets of LH layers below it. 503 is the fourth reflective layer, and layer H is 1 The layer is formed by laminating 7 sets of LH layers below the layer, and 502 is a fifth reflective layer consisting of 1 layer H and 15 sets of LH layers below it. It is formed. Reference numeral 510 denotes a first transmission layer formed by laminating 54 sets of LL layers, and 509 denotes a second transmission layer formed by laminating 70 sets of LL layers. 508 is a third transmission layer formed by stacking 57 sets of LL layers, and 507 is a fourth transmission layer formed by stacking 47 sets of LL layers. Is formed. Reference numeral 5200 denotes an arrow indicating the direction of light incident on the dielectric multilayer film 500, and reference numeral 5300 indicates an arrow indicating the direction of light emitted from the dielectric multilayer film 500.

Reference numeral 511 denotes a first cavity (resonator) between the first reflective layer 506 and the second reflective layer 505, and 512 denotes a second cavity between the first reflective layer 506 and the second reflective layer 505. A second cavity between the third reflective layer 504, 513 is a third cavity between the third reflective layer 504 and the fourth reflective layer 53, 514 is A fourth cavity between the fourth reflective layer 503 and the fifth reflective layer 502.

Said layer of LH, as in Example 1, a layer L which thickness is formed with a film created by S i 〇 _second ion Assis Bok deposition of a quarter wavelength, the thickness is 1 wavelength quarter T i are composed of a layer H formed in 〇 ₂ Lee On'ashisu DOO film, the S i 〇 _second i On'ashisu preparative layer (layer L) 1 layer and T i 0 ₂ Ion'ashisu preparative layer (layer H ) One combined layer is called one set of LH layers.For example, “three sets of LH layers are stacked” means “layer L 'layer Η layer L' layer Η layer L 'layer Each layer is formed one by one in the order of H. "

Similarly, layers of the LL is called the thickness was formed overlapping two layers L which is composed of Ion'ashisu preparative layer of S i 〇 ₂ quarter wavelengths layer substantially one set of LL. Therefore, for example, “laminated with 54 sets of LL layers” means “formed by laminating 108 layers L”.

The thicknesses of the first, second, third, fourth, and fifth reflective layers are 4 times, 4 times, 7 times, 4 times, 1 1 Z 4 times, 15 4 times, 3 1 4 times, respectively. The thickness of each of the first, second, third, and fourth transmission layers is 1084 times, 1400 times, 114 times 4 times, 9 times 4 times, respectively. It is.

The reflectance of each of the first, second, third, fourth, and fifth reflective layers is first, second, third, fourth, Larger in the order of the fifth reflective layer, 24.8%, 81.0%, 95.3 ° /, respectively. , 98.9%, 100%.

It is preferable that each of the above reflectivities be within 3% of the above values. Further, in order to mass-produce an excellent dispersion compensating element as shown in FIG. 6 described below, the reflectance of the first reflective layer should be 23.0 to 35.0%, The reflectivity of the layer is 75.0 to 91.0%, the reflectivity of the third reflective layer is 92.0 to 98.5%, and the reflectivity of the fourth reflective layer is 98.5 to It is preferable that the reflectivity of the fifth reflective layer be 99.3% or more.

FIG. 6 shows the incident light of the incident light that enters the third-order dispersion compensating element using the dielectric multilayer film of FIG. 5 from the direction of arrow 520 and exits in the direction of arrow 530. Is a graph showing the group velocity delay time vs. wavelength characteristic curve (curve indicated by reference numeral 601 in the figure) with respect to, where the vertical axis is the group velocity delay time and the horizontal axis is the wavelength shift from the center wavelength of the incident light. is there. The center wavelength on the horizontal axis is 1550 nm, and the maximum group velocity delay time is 9.6 ps (pyrosecond). The bandwidth as a third-order dispersion compensator is about 2 nm.

The embodiments of the present invention have been described above with reference to one example for each of the third-order dispersion compensating element having the 3 cavities and the third-order dispersion compensating element having the 4 cavities. The present invention is not limited to the examples, and various variations are possible in accordance with the technical concept of the present invention. Even in such a case, the present invention has a great effect.

For example, in each of the above embodiments, an example in which an ion assist film is used for a multilayer film is described. However, if a film is formed by ion assist deposition, a durable and uniform film can be formed, and the quality of the film can be improved. However, the present invention is not limited to ion-assist deposition, and the present invention is not limited to the use of multi-layer films formed by vapor deposition, sputtering, ion plating, and other methods that are widely used. It has an effect.

In addition, the case where the layer H is mainly formed of T i 〇 ₂ (titanium dioxide) has been described. However, the main components of the layer H are not limited to this, and Si (silicon), G e (germanium), T a ₂ 〇 ₅ (tantalum pentoxide), it may be formed by N b ₂ 0 ₅ (niobium pentoxide). These materials are tertiary dispersed in consideration of their physical properties. It is selected and used so as to meet the specifications of the compensating element.

Further, the dielectric multilayer film 3 0 0 described in FIG. 3, and a dielectric multi-layer film 5 0 0 LL layer is a light transmissive layer described in FIG. 5 is formed by a layer of S i 0 _2, This embodiment is characterized in that the lamination of a thick film as in the present embodiment is easy, and the amorphous state containing a lot of fine crystals tends to be formed, and the production yield of a multilayer film is improved. Also, this instead of the LL layer, S i, G e, T i OT a 2 〇 _5, N bz O s may also be used HH layer formed of any applied becomes layers. The HH layer has advantages such as high film thickness detection accuracy with a film thickness monitor and strong stress.

As can be seen from the above embodiment, the third-order dispersion compensating element using the multilayer film of the present invention can sufficiently compensate for the third-order or higher dispersion. The characteristics of the signal light transmitted to the characteristics shown by the graphs 704 and 714 can be improved.

From the above description, the multilayer film constituting the optical component and the optical device according to the present invention can realize a group velocity delay time-wavelength characteristic that is extremely preferable as a third-order dispersion compensating element. By applying this technology to high-speed long-distance communication systems using fibers, it is possible to compensate for third-order dispersion more accurately and with extremely low loss. Optical communication can be realized at a practical cost. By using the optical components and optical devices of the present invention for high-speed and long-distance communication using optical fibers, many devices, facilities, and technologies constructed using conventional optical communication systems of less than OG bps can be used. It can also be used in high-speed communication at 0 Gbps or higher, and the economic effect of the present invention is enormous. Industrial applicability

An optical component according to the present invention and an optical device using the same are indispensable for practical use of high-speed and long-distance optical communication such as transmitting 100,000 km at 40 Gbps. The present invention greatly contributes to the development of the optical communication field.

That is, by using the optical component of the present invention having an excellent group velocity delay-one wavelength characteristic using a special multilayer film as described above in an optical communication system as a third-order optical dispersion compensating element, conventional dispersion compensation can be performed. Only the third-order chromatic dispersion that could not be compensated Can be compensated with extremely low loss, and high-speed and long-distance optical communication can be realized without replacing existing communication equipment such as optical fibers with new ones. The economic effect is enormous. The optical component having a function as an optical dispersion compensator using a special multilayer film according to the present invention is small, suitable for mass production, and can be provided at a low price. The contribution to development is extremely large.

Claims

The scope of the claims

1. An optical component that can compensate for chromatic dispersion (hereinafter simply referred to as dispersion) by using an optical fiber in a communication system that uses a communication transmission line. The film thickness (hereinafter, also simply referred to as the film thickness or film thickness) when considered as the optical path length (hereinafter, also simply referred to as the optical path length) with respect to the light having the center wavelength of the incident light is four minutes. A multilayer film having at least seven laminated films, which is an integral multiple of 1 (e 4), wherein the multilayer film has at least four light reflecting layers (hereinafter, simply referred to as reflecting layers) for incident light. An optical component having a multilayer film formed so as to have

2. The optical component according to claim 1, wherein the multilayer film is formed so as to have different distances as optical path lengths between the reflective layers.

3. The optical component according to claim 1, wherein the multilayer film has seven layers, and the seven layers are a first layer, a second layer, a third layer, and a fourth layer in order from one side in the thickness direction of the film. When the layers are referred to as layers, fifth layer, sixth layer, and seventh layer, the reflecting layers are the first layer, third layer, fifth layer, and seventh layer, and their reflectances are R1, R3, and R, respectively. An optical component characterized in that R 1 ≤R 3≤R 5≤R 7 where 5, R 7.

4. The optical component according to claim 3, wherein a first cavity is formed between the first reflective layer and the second reflective layer in order from a side in a thickness direction of the multilayer film; A second cavity formed between the reflective layer and the third reflective layer, and a third cavity formed between the third reflective layer and the fourth reflective layer. Features optical components.

5. The optical component according to claim 3, wherein the reflectance R1 of the first layer is 50.0% or more and 68.0% or less, and the reflectance R3 of the third layer is 92.0 °. /. Not less than 99.0%, the reflectance R5 of the fifth layer is not less than 99.0% and not more than 99.8%, and the reflectance R7 of the seventh layer is not less than 99.8%. An optical component characterized by the following.

6. The optical component according to claim 3, wherein the seven layers are a quarter of the film thickness and have a higher refractive index (hereinafter, also referred to as a layer H) and a layer having a film thickness of λ. It is composed of multiple sets of layers that combine a layer with a lower refractive index of / 4 times (hereinafter also referred to as layer L). The multilayer film is formed by laminating three sets of layers (hereinafter, also referred to as LH layers) in which layers L and H are combined in this order from one side in the thickness direction of the multilayer film. Layer composed of 32 sets of layers that combine L and layer L (hereinafter also referred to as LL layer), composed of one layer H and 5 sets of LH layers. Layer, layer composed of 43 sets of LL layers, layer composed of 1 layer H and 8 sets of LH layers, 18 sets of LL layers An optical component characterized by being formed by laminating layers, one layer H, and 15 layers of LH layers.

7. The optical component according to claim 6, that the layer H is formed by a layer consisting of either S i, G e, T i 〇 _{_{_{2, T a 2 0 5,}}} N b 2 0 5 Characteristic optical components.

8. The optical component according to claim 7, wherein the layer L is formed of a layer composed of Si ₂ .

9. An optical component that can compensate for chromatic dispersion (hereinafter, also simply referred to as dispersion) by using an optical fiber in a communication system that uses a communication transmission line. The film thickness (hereinafter, also simply referred to as the film thickness or the film thickness) when considered as the optical path length (hereinafter, also simply referred to as the optical path length) for the light having the center wavelength of the incident light is four minutes. A multi-layered film having at least 9 laminated films, which is an integral multiple of 1 (ぇ 4), wherein the multi-layered film has at least five light reflecting layers (hereinafter simply referred to as reflecting layers) for incident light. An optical component characterized by having a multilayer film formed to have

10. The optical part according to claim 9, wherein the multilayer film is formed so that the intervals as the optical path length between the reflective layers are different from each other.

1 1. The optical component according to claim 9, wherein the multilayer film has nine layers, and the nine layers are a first layer, a second layer, a third layer, and a third layer in order from one side in a thickness direction of the multilayer film. When referred to as the fourth, fifth, sixth, seventh, eighth, and ninth layers, the reflecting layers are the first, third, fifth, seventh, and ninth layers. An optical component characterized in that R 1 ≤ R 3 ≤ R 5 ≤ R 7 ≤ R 9 where the reflectance is R 1, R 3, R 5, R 7 and R 9 respectively.

1 2. The optical component according to claim 11, wherein one side of the multilayer film in a thickness direction is provided. Forming a first cavity between the first reflective layer and the second reflective layer, forming a second cavity between the second reflective layer and the third reflective layer, A third cavity is formed between the reflective layer and the fourth reflective layer, and a fourth cavity is formed between the fourth reflective layer and the fifth reflective layer. Optical components.

1 3. The optical component according to claim 11, wherein the reflectance R1 of the first layer is 23.0% or more and 35.0%, and the reflectance R3 of the third layer is 75.0. 5% or more and 91.0% or less, the reflectance R5 of the fifth layer is 92.0% or more and 98.5% or less, and the reflectance of the seventh layer is 98.5% or more and 99. The optical component, wherein the reflectance R 9 of the ninth layer is 99.3% or more.

14. The optical component according to claim 11, wherein the seven layers are a layer having a thickness of 1/4 times λ and a higher refractive index (hereinafter, also referred to as a layer Η). It is composed of a plurality of layers each including a combination of a layer having a lower refractive index of 1/4 (hereinafter, also referred to as a layer L), and the multilayer film is arranged in order from one side in a thickness direction of the multilayer film. A layer composed of two sets of layers (hereinafter also referred to as LH layers) combined in the order of layer Η, and a layer composed of a combination of layers L and L (hereinafter also referred to as an LL layer) ), A layer composed of 54 sets of layers, a layer composed of 1 layer と and 3 sets of layers of L 、, and a layer composed of 70 sets of LL layers Layer, one layer 1 and five sets of LH layers, a layer composed of 57 sets of LL layers, one layer Η and one layer L層 layer with 7 sets It is composed of a layer composed of 47 layers of LL layers, a layer composed of 47 layers of LL layers, and a layer composed of 1 layer of 15 layers and 15 layers of LH layers. An optical component characterized in that:

The optical component according to 1 5. claims 1 to 4, the layers Η is formed by a layer consisting of either S i, G e, T i 0 2, T a 2 0 5, Ν b 2 0 5 Optical part characterized by that

1 6. The optical component according to claim 1 5, optical component layer L is characterized in that it is formed by a layer consisting of S i 0 _2.

1 7. An optical device that can compensate for third-order wavelength dispersion (hereinafter simply referred to as dispersion) by using an optical fiber in a communication system that uses a communication transmission line. In consideration of this, the optical path length for the central wavelength light of the incident light (hereinafter simply referred to as The film thickness (hereinafter also simply referred to as the film thickness or film thickness) when considered as an optical path length is at least an integral multiple of 1/4 (ぇ 4) of the thickness. A multilayer film having a multilayer film having seven layers and formed so that the multilayer film has at least four light reflection layers (hereinafter, also simply referred to as reflection layers) with respect to incident light. An optical device, characterized in that the optical device comprises a part of a component.

18. The optical device according to claim 17, wherein an optical component in which the multilayer film is formed such that an interval as an optical path length between the reflective layers is different from each other is a part of a component. An optical device, comprising:

1 9. The optical device according to claim 17, wherein the multilayer film has seven layers, and the seven layers are, in order from one side in the thickness direction of the multilayer film, a first layer, a second layer, a third layer, When referred to as the fourth, fifth, sixth, and seventh layers, the light reflecting layers are the first, third, fifth, and seventh layers, and the reflectances thereof are R 1 and R, respectively. An optical device characterized in that optical components satisfying R 1 ≤ R 3 ≤ R 5 ≤ R 7 are part of the components, where R 5, and R 7.

20. The optical device according to claim 19, wherein a first cavity is formed between the first reflective layer and the second reflective layer in order from one side in the thickness direction of the multilayer film, An optical component configured to form a second cavity between the second reflective layer and the third reflective layer, and to form a third cavity between the third reflective layer and the fourth reflective layer An optical device characterized in that it is a part of a component.

2 1. The optical device according to claim 19, wherein the reflectance R 1 of the first layer is 50.0% or more and 68.0% or less, and the reflectance R 3 of the third layer is 9 2. 0% or more and 99.0% or less, the reflectance R5 of the fifth layer is 99.0% or more and 99.8% or less, and the reflectance R7 of the seventh layer is 99.8% or more. An optical device characterized in that an optical component is a part of a component.

2 2. The optical device according to claim 19, wherein the seven layers have a thickness of 1/4 times L and a higher refractive index (hereinafter also referred to as a layer H) and a thickness of λ. It is composed of a plurality of pairs of layers each of which is 1/4 times the layer having a lower refractive index (hereinafter, also referred to as a layer L), wherein the multilayer film is sequentially arranged from one side in the thickness direction of the multilayer film Layers composed of three sets of layers (hereinafter also referred to as LH layers) that are combined in the order of Layer composed of 32 sets of layers combining layer L (hereinafter also referred to as LL layer), layer composed of 1 layer H and 5 sets of LH layers , Layers composed of 43 sets of LL layers, layers composed of 1 layer H and 8 sets of LH layers, and 18 layers of LL layers laminated The optical component formed by each layer of the layer composed of one layer and the layer composed of one layer H and 15 layers of the LH layer shall be part of the component parts. An optical device characterized by the above-mentioned.

2 3. The optical device according to claim 2 2, wherein the layer H is formed by a layer consisting of either S i, G e, T i 〇 _2, T a ₂ 〇, N b ₂ 〇 ₅ An optical device comprising an optical component as a part of a component.

24. The optical device according to claim 23, wherein an optical component in which the layer L is formed of a layer made of Si02 is a part of a component.

2 5. An optical device that can compensate for third-order wavelength dispersion (hereinafter simply referred to as dispersion) by using an optical fiber in a communication system that uses a communication transmission line. The center wavelength of the incident light As a result, the film thickness (hereinafter, also simply referred to as the film thickness or film thickness) when considered as the optical path length for the light having the center wavelength of the incident light (hereinafter, also simply referred to as the optical path length) is obtained. It has a multilayer film having at least 9 laminated films that are integral multiples of 1/4 (λ / 4) of the above, and the multilayer film has at least five light reflection layers (hereinafter, referred to as incident light). An optical device comprising, as a part of a component, an optical component having a multilayer film formed so as to have a reflective layer.

26. The optical device according to claim 25, wherein an optical component in which the multilayer film is formed such that an interval as an optical path length between the reflective layers is different from each other is a part of a component. An optical device, comprising:

27. The optical device according to claim 25, wherein the multilayer film has nine layers, and the nine layers are, in order from one side in a thickness direction of the multilayer film, a first layer, a second layer, a third layer, When the fourth layer, the fifth layer, the sixth layer, the seventh layer, the eighth layer, and the ninth layer are referred to, the reflection layer is the first layer, the third layer, the fifth layer, the seventh layer, and the ninth layer. Assuming that the reflectance is R1, R3; R5, R7, R9 respectively, the optical components with R1 ≤ R3 ≤ R5 ≤ R7 ≤ R9 are part of the components An optical device, characterized in that:

28. The optical device according to claim 27, wherein one side in the thickness direction of the multilayer film is provided. Forming a first cavity between the first reflective layer and the second reflective layer, forming a second cavity between the second reflective layer and the third reflective layer, A third cavity is formed between the reflective layer and the fourth reflective layer, and a fourth cavity is formed between the fourth reflective layer and the fifth reflective layer. An optical device characterized in that an optical component to be formed is a part of a component.

2 9. The optical device according to claim 27, wherein the first layer has a reflectivity R 1 of 23.

0% or more and 35.0% or less, the reflectance R3 of the third layer is 75.0% or more and 91.0% or less, and the reflectance R5 of the fifth layer is 92.0% or more 9 8.5% or less, the reflectance R7 of the seventh layer is 98.5% or more, 99.3% or less, and the reflectance R9 of the ninth layer is 99.9.

An optical device, wherein an optical component that accounts for 3% or more is part of a component.

30. The optical device according to claim 27, wherein the seven layers are a quarter of the film thickness and have a higher refractive index (hereinafter, also referred to as a layer H). It is composed of a plurality of layers each including a combination of a layer having a lower refractive index of 1/4 (hereinafter, also referred to as a layer L), and the multilayer film is arranged in order from one side in a thickness direction of the multilayer film. A layer composed of two sets of layers in which layers L and H are combined in this order (hereinafter also referred to as LH layers), a layer composed of layers L and L (hereinafter also referred to as LL layers) ), A layer composed of 54 sets of layers, a layer composed of 1 layer H and 3 sets of LH layers, and a layer composed of 70 sets of LL layers. Layer, one layer H and five sets of LH layers, a layer composed of 57 sets of LL layers, one layer H and one layer of LH Laminate 7 sets with layers The optical layer is composed of a layer composed of 47 layers of LL layers, a layer composed of one layer H and 15 sets of LH layers. An optical device comprising a part as a part of a component.

The optical device according to 3: 1. 3. 0, optics layer H is formed by a layer consisting of either S i, G e, T i 〇 _{_{_{2, T a 2 0 5,}}} Ν b 2 0 An optical device characterized in that parts are part of components.

32. The optical device according to claim 31, wherein an optical component in which the layer L is formed of a layer composed of Si ₂ is a part of a component.